Scientists in New South Wales, Australia have devised a new way of catching and removing introduced carp from rivers in the region.
They have managed to isolate a key chemical in the female carps breeding pheromones used to attract male fish for spawning.
This chemical is surgically implanted into a female fish which is then placed in a trap to await the attentions of amorous males.
Normally the chemical attractant is only produced by the female fish for less than an hour, but with the implant the fish can lure in suitors for at least two weeks. Beguiled by the intoxicating female, the male fish shed their inhibitions and are far less wary of entering the trap. A trial began at the end of October at Hillston on the lower Lachlan River which will be closely monitored for 10 days and the catch numbers compared with those from current trapping methods.
The Common carp, (Cyprinus carpio) was introduced to Australia by European settlers in the 18th century as a food source. They have rapidly spread throughout freshwater environments in the country and are now estimated to make up around 80% of the biomass of most inland river systems. In doing so, they have pushed many native fish species to the edge of extinction.